Apparatus for grinding bushings on centerless grinders



E. W. BUEBEL June 22, 194:8,

APPARATUS FOR GRINDING BUSHINGS ON CENTERLESS GRINDERS Filed July 18, 1945 li dyal' WBue bel m/ JM Q Patented June 22, 1948 APPARATUS FOR GRINDING BUSHINGS ON CENTERLESS GRINDERS Edgar W. Buebel, Baltimore, Md., assignor to lihe Glenn L. Martin Company, Middle River, Md., a corporation of Maryland Application July 18, 1945, Serial No. 605,763

4 Claims.

My invention relates to apparatus for centering cylinders in a centerless grinder and more particularly a device that provides for grinding the external periphery of a bushing concentric to its bore when used in conjunction with a centerless grinder.

The use of centerless grinders to grind the outside surfaces of cylindrical parts to tolerances of micro-inches is well known. In accordance with prior art practices the part is not held, but laid on a work rest blade between a regulating or feeding wheel. The regulating wheel is set at an angle with respect to the axis of the grinding wheel so that as the regulating wheel rotates there will be a component of force created lengthwise of the work support blade tending to urge the part being ground across the grinding .surface of the grinding wheel. This method has many advantages, but as it is necessary for the part to be laid in position for grinding without regard to the center of its bore it is impossible to grind apertured work pieces, like bushings, that must be ground to close limits of concentricity. A former method of working such pieces requires that the work piece be press fit mounted on an arbor held between fixed centers. The grinding wheel is then run back and forth in contact with the worked surface until the piece is ground to the desired size. This method permits the circular exterior of the work piece to be ground to close tolerances relative to the centerline of the aperture, however, as each piece requires a machine setting-up operation it is costly and slow. Work pieces worked in accordance with this method also are susceptible to considerable scoring of the bore by particles of abrasive material deposited on the arbor surface.

The present invention provides an adjustable bracket having a pivoted arm adapted to position an arbor carrying a cylindrical work piece to be ground so that the piece is fed to the grinding wheel of a conventional centerless grinder and held on a given axial centerline until the external periphery thereof is ground concentric to the given centerline and position said piece for further movement across the face of the grinding wheel, whereby the concentricity of the center of a drilled hole in a work piece is held to microinch tolerances relative to the center of the periphery of the work piece. Its design provides for changeability of arbors over a wide range of sizes. The shortness of the arbor relative to the travel of the work piece and the pivoting arrangement f the arbor holding blade is such as to greatly reduce exposure of the interior sur- 2 face of the bushing to score producing particles of abrasive.

It is among the objects of my invention to provide a means for centering cylinders for grinding in a centerless grinder wherein an adjustable bracket supporting a pivotally mounted blade is arranged to position a centered arbor carrying a cylindrical centered work piece through an initial stage of grinding in a centerless grinder.

Another object of this invention is to provide a means according to the preceding object of automatically grinding the external surface of a bushing concentric to the center of the periphcry of the aperture in the bushing.

Other objects of this invention will become apparent from the following description in which reference is made to the accompanying drawing wherein like numbers refer to like parts in the different views.

In the drawing:

Figure 1 is a perspective view of the device of my invention in operating position feeding a bushing to the grinding wheel and showing two previously feed bushings in advanced stages of being ground.

Figure 2 is a perspective view of the device in open position showing the blade carrying the arbor in vertical position.

Figure 3 is a fragmentary vertical sectional view of a grinder showing the relative position of the arbor to the regulating and grinding wheels.

Referring in detail to the drawings I have illustrated the preferred embodiment of my invention as an improved feeding device for feeding cylindrical work pieces to a conventional centerless grinder. This type of grinder is known in the art as an in-feed grinder having a regulating wheel l0 disposed at a slight angle to the axis of a grinding wheel H so that as the feed wheel rotates it creates a slight urge upon the work piece tending to receive and draw it across the face of the grinding wheel. The work piece is supported by a work rest l2 positioned parallel to the face of the grinding Wheel l I across which it moves as the grinding operation is performed. The spacing of grinding wheel H from the feed wheel l0 determines the amount of out.

The device l3 of my invention is mounted on the side wall M, or support of a centerless grinder as illustrated in Figure l. A supporting bracket [5 having a slotted vertical portion Iii and a tongued platform I! is adjustably-mounted on wall I and secured thereto 'by stud bolts I8 inserted through vertical slots [9. Vertical adjustment of the support is accomplished by loosening bolts l8 and moving the bracket l vertically as required for positioning various sized work pieces.

Slidably mounted on the platform 9? of bracket is is a block member 2% formed with a base 2i and two upright side members 22 arranged to form a channel 33. Base 2| of the block all is formed with agroove 23 arrangedtoreceive tongue 2 of theplatform H forming a longi tudinal dovetail joint between the block 2&3 and platform ll which restricts the block 253 to longitudinal movement relative to the platform 52. Base 2! is provided with extension 25 which extends outward and downwardly from-basal? to form an angled adjustingbar apertured.to receive an adjusting means. Extending -outwardly from platform ll is a threaded Mid E55 aligned with the aperture in the angled end of extension 25 to provide an adjusting -means"by which block 2d may be horizontally positioned relative to platform ll and secured in place by means of an outer nutEl and an innernut positioned to secure angled'portiondil or the extension 25. This lon itudinal adjusting means, providing horizontal movement of block'flil along axis parallel to the grinding wheel l l, provides thy-device with a wide range of adjustment for working pieces of various lengths.

A bar of blade 3 l is pivotally mounted-in channel 2% of the block fill so thatthe end portion thereof can be raiseda'way'from the grinding wheel ii to anupright, or vertical, position as shown in Figure 2.. Blade-3i is'iormed with a socket 333 in the endportions? to receivevarbor Zi i held in position by locking screws 3'! or alike holding means. "The opposite end .ofblade 5:33 is drilled ,to receive a rotative pivot pin or a like pivoting means, positioned in holes, or sockets, formed-in the side members 22 ofblock I have found it desirable towarrangewthe point of pivot of the aforedescribed pivoting means beyondthe center of block 2i3. away from the grinder a sufiicient distance so that the natural tendency of lthe blade is to droptoca horizontal or engaged position when moved'forward "from a vertical position. With this ar-- rangement I utilize the unbalanced -weight-of blade 85, which is prferablylmade from heavy wear resistant bar stock -andthe snugness offit between blade fil-in channel-.36 to securea firm holding means for the workpiece -33 during the grinding operation. -Blade 3l provided with a handle 35 positioned adjacent the pivot bywhich the blade 35 can be readily moved to the vertical position shown in Figure 2.

The arbor 3 3 is proportioned-tobeinserted in socket-i3 of the bladed! and isformedwith a shoulder 38. The receiving portion ofarbor -Zi l is formed to anydesired diameter-determined by the diameter of the "aperture. in the bushing to be worked and ofsufficient length tosupport the work piece 35-3 concentricto the axial centerline of the arbor a: as the work piece moves across the work face of grinding-wheel H 'for a -distance equal to the length of. the workpiece 3 as shown in Figure 1. Thelength of arbor 36 is varied in accordance with the lengthof work piece 3% to be ground. The length ofthereceiving portion of arbor 35 should be approximately one and one half times the length ofthe workpiece in order tohold it in alignment during the first stage of thegrinding operationin which it is ground overits entire length, thereby removing any eccentricityof-its external surface-relative to the bore.

The operation of -my device-may l be brie'fly wheel-1 I. -in-Figures-1and-3. The arbor M is raised and tically adjusted so that' wo'rk piece 35) will rest upon work rest 2. The block 23 is longitudinally adjusted to place shoulder 33 of the arbor 3 1 adjacent work rest l2 so that work piece 353 in its initial position will have a feed-in contact of approximately & of an inch with the grinding This set-up positioning is illustrated held'in 'vertical. position until the grinding wheel H and feed wheel II] are brought up to full operating speeds by means of an electric motor, not

shown; or some other like driving means.

The arbor 33 is then pivoted to grinding position shown in Figure 3 with work piece 39 being moved into engagement with the regulating wheel 16 and grinding wheel ll. As the regulating wheel Hl draws the work piece 39 across the face of the grinding wheel H the external periphery of the work piece is ground truly concentric to the hole in the work piece which is held to the axial centerline of arbor 3 3. After having traveled the length of the work portion of the arbor-34, which is approximately one and one half times the length of the work piece, the work piece 39 in its true concentric formrnoves clear of the arbor and along the work rest 2 to be completely-ground in the conventional manner (See Figure 1).

Although I have described both vertical and horizontal adjustments in detail it will be understood thateither adjustment can be varied independent of the other, such adjustment, or adjustments, being governed by the length and diameter of the piece to be ground. Also, it will be understood that once a setting is established no further-adjustment will be required for a given size piece irrespective of the number of pieces ground.

Although the preferred embodiment of my invention has been shown as a feeding device as shownand described in detail and its environment referred to as working bushings, it will be appreciated that certain changes, alterations, modifications, and substitutions can be made without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A centering device for a centerless. grinding machine having a work rest positioned between a regulating wheel and a grinding wheel mounted upon a base, comprising an adjustable supporting bracket mounted on said base, a block formed witha base portion and a channel portion adjustably mounted onthe supporting bracket, a bladepivotally mounted inthe channel of said block and having a socket formed in one end, an arbor formed with a receiving portion atone end adapted to receive and hold an apertured work pieceand an inserting portion at the opposite end whichprovides for mounting in said pivoted blade, and a handle mounted in said blade at the point-of fulcrum providing manual: means for pivotally moving the blade to a longitudinal positionrelative to the work rest with the arbor mounted in the-end of said blade positioned longitudinally adjacent the 'work. rest and transversely adjacent the grinding wheel.

7 2. A positioning device fora grinding machine having a work rest,--a grinding wheel-and-a regulating wheel positioned to receive and grind a cylindrical Work piece, comprising a supported base having a channeled portion, a blade movably mounted in said channel with an end formed with a socket and positioned adjacent the grinding wheel, an arbor adapted to be inserted in said socket and having a receiving end adapted to receive a cylindrical work piece, and adjusting means by which said work piece is moved into grinding contact with the grinding wheel.

3. A positioning device for a grinding machine having a work rest, a grinding wheel and a regulating Wheel mounted on a base, comprising a supporting bracket mounted on said base, a channeled block adjustably mounted on said bracket, a blade adjustably mounted in said channel transversely to the grinding wheel, an arbor carried by said blade and formed with a Work receiving portion, said work piece receiving portion being positioned and arranged to support a work piece for rotational and axial movement in contact with said grinding wheel and supported by the work rest.

4. A centering device for a centerless grinding machine having a work rest, a grinding wheel and a regulating wheel mounted on a base having a side wall and arranged to grind cylindrical Work pieces, comprising a bracket mounted on said side wall with adjustable attaching means and formed with a tongued platform portion, a 30 2,314,533

block formed with a base and side members forming a longitudinal channeled section above the base which is grooved to form a tongue and groove joint with said platform providing a longitudinal slide fit therewith, an extension extending from said base and arranged to provide longitudinal adjusting means between the block and platform, a pivoted blade having a socket formed in one end and adapted to be mounted in said channel, an arbor formed with a work receiving portion of approximately one and one half times the length of the work piece to be ground and having a securing portion adapted for insertion in said socket, an actuating handle for pivotally moving said blade carrying a work piece to a grinding position on the work rest in contact with the grinding and regulating wheels.

EDGAR W. BUEBEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,814,362 Booth July 14, 1931 1,834,158 Johnston Dec. 1, 1931 1,874,301 Jones Aug. 30, 1932 2,023,720 Asbridge Dec. 10, 1935 Wallace Mar. 23, 1943 

